Greg Hodge beams at me from the hole of a crevasse. Notoriously difficult to see, crevasses are often covered by bridging snow which can collapse under the weight of a person, or be strong enough to allow a heavy vehicle to cross. On this occasion I was on a training exercise, and my entry into the "slot" was a controlled one. The walls of the crevasse reveal amazing ice flowers, growing in the freezer-like conditions.